It's been easy to be a right-wing politician in New Zealand the past couple of years. It looks like it's about to get a lot trickier, as Garrett goes

Remember the "five-headed monster", John Key's attempt to scare voters in his direction at the last election? Well, it's back, or will be soon, as the politicians try to figure out the implications of ACT's disintegration as a credible political voice.

David Garrett's resignation from ACT today takes us to a whole new level of uncertainty, while we wait to learn whether he will stay as an independent or leave parliament altogether. But it seriously undermines ACT and raises any number of questions about the right's electoral chances.

Back in October 2008, Mr Key, then-Opposition leader, raised the prospect of Labour being joined in power by the Greens, New Zealand First, the Maori Party and the Progressives.

Key said that a "Helen Clark-led government cobbled together with all sorts of different parties" with "competing interests" would not be in the best interests of New Zealand during a period of "difficult economic times to manage". 

Instead, he put together a four-headed monster, with ACT, the Maori Party and United Future, and it turns out that the "competing interests" have actually been quite a useful thing for Key.

Until now, that is. Now, it's a mess, and sadly for the PM it's on his right, not in the centre where he could easily fill the void. Suddenly, Labour leading a multi-headed government in 2011 seems a little less impossible (although Labour supporters might ask whether that's really best for the future of the party; but that's a post for another day).

The growing public perception of ACT is that its MPs are just unstable and more than a little odd. The pure convictions, fringe quirkiness, and bold ideas that appealed to at least a few percent of New Zealanders has been replaced by a sense of weirdness.

Voters are asking, is ACT even a party any more or just a group of individualist individuals at war?

Although, having said that, the fringe left can be just as scratchy and internecine. Look back at how the Alliance fell apart. ACT MPs should pay some attention to what happened back in 2001-02, especially those trying to undermine leader Rodney Hide. Politics, remember, comes down to a numbers game in the end.

Labour stuck with Anderton, because he had a safe seat (and a long-term relationship with Cabinet ministers), choosing to play nice with the Progressives. It ran hard against Laila Harre and Willie Jackson to keep them out of parliament.

In the same vein, National will side with Hide against any defectors. Although the significant difference is that while Anderton owned the Sydenham seat, Hide is only borrowing Epsom from National for as long as they want to indulge him.

With ACT looking so unpalatable, it's hard to imagine them being able to win a party vote sufficient to deliver more than one or two MPs next year. At which point National has to ask, L'Oreal-like, 'are they worth it'?

The problem for National is that it then has to try to make up those numbers itself. It can probably count on Peter Dunne, although Dunne's hold of Ohariu isn't as solid as it used to be.

But is a National-Maori Party-United Future government attractive to enough people, especially on the back of the Foreshore and Seabed reforms? Would the Maori Party even stay with National?

How does it compare to a Labour-Greens-New Zealand First (-Maori Party) government? This, my friends, could make for an interesting election year.